In the prior art auto-control pencil, the pencil lead is driven in a transfer tube and a movable claw element. However the pencil lead is easy to break as a great force is applied therein. The spring in the transfer tube only has the function of pushing the pencil lead instead of preventing the pencil lead from breaking. If the force applied therein is too great, the pencil lead will be compressed to break, specifically it is easily occurred as the pencil is operated by children because the children cannot apply a proper force to the pencil.